Elements of Music

20 21 chord progrEssIons tonic, dominant, and subdominant Chords take on the identity of the station upon which they are built, reinforced by the tone tendencies, so that as the chords move in a progression or succession, they push and pull on their neighbors, reinforcing the key. As notes in a chord collaborate to emphasise one pitch, all chords collaborate to strengthen or weaken the tonic. The strongest progressive motion a root can have is a fifth, either downwards or upwards, highlighting the close kinship and relative gravity of three consecutive pitches on the circle of fifths. The most basic chord movement then is tonic I to subdominant IV to dominant V and back to tonic I, although other triads in the scale can substitute for these three basic functions without sacrificing wholly the function or temporal meaning of their placement below. I and iii share 3 and 5, so can substitute for each other. Likewise, ii and IV share two tones, as do vi and I, and V and vii. The more common tones, the smoother and more gradual the harmonic motion. There are essentially three states in tonal harmonic progression starting, departing, and returning, which are repeated and cycled to reinforce the tonic. Chords with more symmetrical intervals thirds are unstable or require resolving, and have a dominant function, while harmonies having perfect fourths and fifths the only asymmetric intervals are more restful and are nondominant. I ii iii IV V vi viio I 135 246 357 461 572 613 724 135